How do herbicides like Roundup work?

Herbicides like Roundup are products that inhibit plant and weed growth in a very specific way. Explore the biochemistry behind glyphosphate-based herbicides in this episode of HowStuffWorks.com.

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Episode Transcript

Speaker 1 (00:00):
Welcome to Brainstuff from house Stop works dot com where
smart happens. Hi Am Marshall Brain with today's question, how
does the herbicide round up work? Round Up, which is
a trade name used by Monsanto, and other herbicides based

(00:23):
on glyphosphate, which is the generic name, are probably the
most commonly applied weed killers in use today. These herbicides
are used by everyone from farmers to foresters, to gardeners
to biologists who are trying to control invasive exotic plants.
Glyphosphate based herbicides all work on the same biochemical principle.

(00:44):
They inhibit a specific enzyme that plants need in order
to grow. The specific enzyme is called EPSP synthase. Without
that enzyme, plants are unable to produce other proteins essential
to growth, so they yellow and dye over the course
of several days or weeks. Majority of plants use this
same enzymes, so almost all plants to come to round up.

(01:08):
If you've read the How Stuff Works article called how
Cells Work, you know a good bit about DNA and
how it produces enzymes in the same way that many
antibiotics gum up enzyme production to kill bacteria. Glyphosphate gums
up enzymes and plants to kill them. Glyphosphate kills plants
like antibiotics kill bacteria. If you've been following farming news

(01:33):
or the genetically modified food debate, you know that glyphosphate
tolerance seeds are now available. You can buy genetically modified corn, soybeans,
and so on that are immune to glyphosphate. These plants
use an enzyme that performs the same function as EPSP synthas,
but is not inhibited by glyphosphate. Round up will kill

(01:54):
almost any plant, including aquatic plants, so you want to
be sure to avoid spray drift onto other plants or
into the water. Any pesticide should be applied carefully. Do
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works dot com. For more on this and thousands of

(02:15):
other topics, go to how stuff works dot com and
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